1. Technical Field
The present invention relates to an optical device having a light modulation unit, and a projector including this optical device.
2. Related Art
A projector which contains a light modulation unit for modulating light emitted from a light source according to image information and a projection unit for expanding and projecting the light modulated by the light modulation unit is known. For example, the light modulation unit is an active matrix drive type liquid crystal panel having a pair of substrates into which liquid crystals are sealed. In this case, the liquid crystal panel is held by a frame to be used as an optical device.
The liquid crystal panel generates heat when a liquid crystal layer, various types of wires, a black matrix and other components of the liquid crystal panel absorb light emitted from the light source. The generated heat deteriorates the liquid crystal panel in some cases. For overcoming this problem, a technology which cools the liquid crystal panel by supplying air to the optical device has been proposed (for example, see JP-A-2002-107698).
A projector shown in JP-A-2002-107698 includes an optical device (liquid crystal display element) having a transmission type liquid crystal panel and a frame, and a fan for supplying air to the optical device. The frame is so constructed as to hold the outer periphery of the liquid crystal panel, and a slope is formed at the end of the frame. Air supplied from the fan flows along this slope to be smoothly guided to the surface of the liquid crystal panel and used for cooling the liquid crystal panel.
According to the technology disclosed in JP-A-2002-107698, air is introduced to the surface of the liquid crystal panel by the function of the slope provided on the frame. However, since the outer periphery of the surface of the liquid crystal panel is covered by the frame with a step formed between the surface of the liquid crystal panel and the surface of the frame, there is a possibility that air is not guided to the entire area of the surface. In this case, the liquid crystal panel cannot be sufficiently cooled. When the number of revolutions of the fan is raised to sufficiently cool the liquid crystal panel, noise increases and thus makes an observer uncomfortable in some cases while observing image light projected from the projector.